[PATCH] net: dhcp6: Fix OPT_BOOTFILE_PARAM parsing

[seanedmond]

From: Sean Edmond <seanedm...@microsoft.com>

RFC 5970 states that OPT_BOOTFILE_PARAM (option 60) can be
multiple parameters that start with a 16-bit length field followed
by the parameter. For example:
[ param-len 1 (16-bits) ] [ parameter 1 (variable length) ]

This fix ensure we're considering "param-len 1" in the parsing.

Signed-off-by: Sean Edmond <seanedm...@microsoft.com>
---
 net/dhcpv6.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/net/dhcpv6.c b/net/dhcpv6.c
index 73a1067877..4aea779f6f 100644
--- a/net/dhcpv6.c
+++ b/net/dhcpv6.c
@@ -304,7 +304,7 @@ static void dhcp6_parse_ia_options(struct dhcp6_option_hdr 
*ia_ptr, uchar *ia_op
 static void dhcp6_parse_options(uchar *rx_pkt, unsigned int len)
 {
        uchar *option_ptr;
-       int sol_max_rt_sec, option_len;
+       int sol_max_rt_sec, option_len, param_len_1;
        char *s, *e;
        struct dhcp6_option_hdr *option_hdr;
 
@@ -390,14 +390,23 @@ static void dhcp6_parse_options(uchar *rx_pkt, unsigned 
int len)
                case DHCP6_OPTION_OPT_BOOTFILE_PARAM:
                        if (IS_ENABLED(CONFIG_DHCP6_PXE_DHCP_OPTION)) {
                                debug("DHCP6_OPTION_OPT_BOOTFILE_PARAM 
FOUND\n");
+                               /* if CONFIG_DHCP6_PXE_DHCP_OPTION is set the 
PXE config file path
+                                * is contained in the first OPT_BOOTFILE_PARAM 
argument
+                                */
+                               param_len_1 = ntohs(*((u16 *)option_ptr));
+                               option_ptr += sizeof(u16);
+                               if (param_len_1 + sizeof(u16) > option_len) {
+                                       debug("Invalid BOOTFILE_PARAM 
param_len_1. Skipping\n");
+                                       break;
+                               }
 
                                if (pxelinux_configfile)
                                        free(pxelinux_configfile);
 
-                               pxelinux_configfile = (char 
*)malloc((option_len + 1) *
+                               pxelinux_configfile = (char 
*)malloc((param_len_1 + 1) *
                                                      sizeof(char));
                                if (pxelinux_configfile)
-                                       strlcpy(pxelinux_configfile, 
option_ptr, option_len + 1);
+                                       strlcpy(pxelinux_configfile, 
option_ptr, param_len_1 + 1);
                                else
                                        printf("Error: Failed to allocate 
pxelinux_configfile\n");
 
-- 
2.40.0